Sonic Devices Demand Greater Research

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Throughout history, sound has been used to enhance the effectiveness of conventional and psychological military operations. Today, warfighters use sonic devices for a wider variety of functions, including clear communication in the field at standoff distances, warning civilians away from bases, and non-violently deterring potential enemy combatants.

The Joint Nonlethal Weapons Program sees the near future potential for sonic devices as not only improving existing functions, but to be integrated with other nonlethal weapon systems.

Private firms have also worked to expand the role of these devices beyond their place in the military’s force escalation toolkit. The same devices used by the military have seen numerous applications in emergency responses, including directing port traffic during earthquake relief efforts in Haiti and broadcasting evacuation orders during a Colorado wildfire.

As sonic technologies grow in popularity and use, there is an increasing risk that improper deployment of their potentially debilitating effects could result in regulations that restrict their legitimate applications. Frequent problematic use by civil authorities is poisoning the public’s understanding of these technologies. This can already be seen in the media where the Long-Range Acoustic Device, a hailer used by the military for over a decade, is being referred to as a “sound cannon” due to its misuse during public protests by police forces.

Together with legal challenges and condemnation by advocacy groups, public opposition may serve as the foundation for an overly restrictive government response, which would require the military and members of the industrial base to defend the merits of sonic devices. Further research into the human impacts of high intensity audible sound would bolster efforts to preserve the unique capabilities of sonic devices.

The effects of audible sound in the frequency range of 20Hz to 20kHz have been thoroughly researched in laboratory and environmental studies. Sound above a certain intensity measured in decibels can cause disorientation, pain and temporary or permanent threshold shifts in hearing. Guidelines on safe noise exposure vary, but sound over 100 decibels can cause hearing loss over the course of minutes, and at 120 decibels impulse sound begins to produce a pain response. Sound over 140 decibels can cause near-immediate hearing damage. Sonic devices currently employed by the military and law enforcement can produce sound in excess of 150 decibels.

What the existing literature is lacking are studies at the intersection of theory and practice. Most studies performed in a controlled environment exploring the biological effects of short-term exposure to intense sound focus on the 80-120 dB range. Studies that explore exposure to higher intensity sound typically focus on sources of environmental noise such as sirens or industrial equipment. Unlike sonic devices and nonlethal weapons, which produce extremely intense sound over short intervals, environmental noise effects accumulate over time, making such studies a poor point of comparison.

Case studies of people previously exposed to high intensity audible sound would fill gaps in the existing literature. Examination of individuals affected by sonic devices, or exposed to environmental sound of comparable intensity, would allow for a better understanding of the physical and behavioral effects high intensity sound produces in humans.

A better understanding of the effects will assist in the creation of widely acceptable standards for use, guide safety innovations and inform public opinion.

Misuse of sonic devices has already triggered a public backlash. In recent years, U.S. police settled multiple lawsuits alleging that the misuse of LRADs during public protests resulted in permanent hearing loss. One noteworthy suit found that improper use of the sonic devices can qualify as excessive force. Police have also employed acoustic devices during protests in Malaysia and Hong Kong. Although there have been no official reports of excessive use in these circumstances, the proliferation of these devices has been met with unease. Several advocacy groups including the Better Hearing Institute, Amnesty International and the International Network of Civil Liberties Organizations, have raised concerns over the use of sonic devices by authorities. Amnesty International has gone so far as to call for a suspension of the use of acoustic devices with a deterrent function by law enforcement, until an independent body of experts can “demonstrate a legitimate and safe use”.

At the international level, there is precedent for restricting or banning the use of nonlethal weapon technologies that cause permanent sensory damage. After a concerted lobbying effort by the Red Cross, the use and transfer of laser weapons designed to permanently blind or damage the vision of enemy combatants was banned by the Convention on Certain Conventional Weapons. Last year a CCW working group report noted that the use of sonic devices to inflict pain raises questions about their legality under international humanitarian law and the potential need for international regulation. Their report cites a lack of data about acoustic devices’ specifications and effects as a cause of public anxiety. Further research into the effects generated by the devices will directly address the concerns of advocacy groups and prospective regulators.

Sonic devices offer warfighters and civilian officials unique tools for a growing variety of situations, including controlled force escalation and emergency response, but abuse of their capabilities threatens these technologies’ future use. Further study of the human effects caused by sonic devices will provide members of the military and industry the evidence needed to assuage public fears and preserve the development and use of these systems. 

Jens Pedersen-Giles is a junior policy fellow at NDIA.

Topics: Emerging Technologies